Apparatus for flame treating metal sheets



Feb. 13, 1962 A. STUCHBERY 3,021,125

APPARATUS FOR FLAME TREATING METAL SHEETS Filed May 8, 1958 2 Sheets-Sheet l I n ven tor ArZk a)" Ze Zzle E'l/(kiyy WM, m rlin? Attorney Feb. 13, 1962 A. STUCHBERY APPARATUS FOR FLAME TREATING METAL SHEETS 2 Sheets-Sheet 2 Filed May 8, 1958 I nventor w W w M .m B d T u I H F 3,621,125 APPTUS FUR FLAME TREATING METAL SHEETS Arthur Leslie Stuchbery, Enficld, England, assignor to The Metal Box Company Limited, London, England,

a British company Filed May 8, 1958, Ser. No. 734,033 8 Claims. (Cl. 263-6) This invention relates to machines for liquid-coating metal articles and in particular to machines for coating the surface of a metal article with lacquer or other liquid which it is desired shall provide the surface with an uninterrupted coating.

As is well understood, when coating metal articles with some types of coating liquid, particularly articles of tinplate, it is difficult to avoid the condition known as flecking, a term used to describe small areas surrounded by coating liquid but to which none of the liquid has adhered. The causes of flecking are not fully understood, but it is known that they can be reduced by heating the surfaces to be coated prior to the coating thereof and it has heretofore been customary to pre-stove the articles before passing them to the coating machine. This practice, however, is not fully satisfactory due primarily to the heavy additional cost of the pre-stoving operation, and in part to the fact that after pre-stoving the articles must be transferred from the pre-stoving apparatus to the coat ing machine with the result that some of the articles may again become subject to flocking during coating.

It is a main object of the present invention toprovide a new coating process and coating equipment which is so constructed as to eliminate the need for pre-stoving as previously practised and which, by ensuring treatment of the articles actually in the coating equipment immediately prior to the coating thereof, reduces the possibility of flecking to a minimum not heretofore possible.

According to the present invention there is provided a process for the liquid-coating of metal articles which consists of applying a flame to the whole of the surface of the article to which a liquid coating is to be applied, drying said surface to remove accumulated moisture of condensation therefrom, and applying a liquid coating to the heated and dried surface.

Further according to the present invention there is provided a machine for liquid-coating metal articles in which articles to be coated are moved in succession byconveyor means to and from a liquid applicator, wherein prior to application of coating liquid thereto an article is moved by the conveyor means first past a flame applicator by which a flame is applied to the whole of the article surface to be coated and then past a dryer device adapted to remove accumulated moisture of condensation from said article surface.

In order that the invention may be clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 is a longitudinal section through a part of a machine for liquid coating flat tinplate sheets, and

FIGURE 2 is a top plan of FIGURE 1.

Referring to the drawings, tinplate sheets to be liquidcoated are fed into the machine one at a time from a stack thereof, not shown, by a first endless conveyor 1 by which they are delivered to the upper run of a second endless conveyor 2 which is disposed at a level below that of the first conveyor. The second conveyor 2 in turn delivers sheets in succession to a third endless conveyor 3 by which the sheets are fed past the liquid-applying apparatus, not shown.

In accordance with the invention the upper surfaces of the sheets are treated before being fed by the endless 3,@Zl,l25 Patented Feb. 13, 1962 conveyor 3 to the lacquer applying apparatus and the treatment is effected by a flame applicator which consists of a gas burner adapted to project a flame towards and against the surface of the sheet to which the lacquer is to be applied. The gas burner is located above the path of the sheets and is arranged to direct a flame downwards and transverse to the direction of movement of the sheets. The burner consists of a manifold 4, fitted with a plurality of jet nozzles 5, the nozzles 5 being disposed in endwise overlapping relation as illustrated in FIGURE 2 so as to provide a continuous sheet of flame 6, FIGURE 1, transverse to the direction of movement of the sheets.

As can be seen from FIGURE 1, the burners are so disposed as to direct the flame 6 against the upper surface of a sheet during transfer thereof from the first conveyor 1 to the second conveyor 2, the transfer of the sheets being effected by gravity and due to the momentum which they have on leaving the conveyor 1. Normally it is found that the sheets on leaving conveyor 1 will fall properly on to conveyor 2, but to guard against the contingency that the rear parts of the sheets tend to fall differently during transfer, one or more freely rotatable control guide rollers 7 are provided which may be engaged by the underside of the sheet to assist in guiding the rear part of the sheet through the flame 6.

It will be understood that the manifold 4 is connected in any suitable manner with sources of gas and air and that such sources may be manually or automatically controlled. The arrangement may be such that the flame is ignited from a pilot jet, not shown, either manually or automatically and it will be further understood that when the flame is automatically controlled it will be ignited when the operation of the machine is commenced and will be extinguished when the machine operation is discontinued.

twill be understood that the sheets will not be delivered in succession in end to end engagement with each other and that accordingly there will be spaces between successive sheets. 'To avoid the flame 6 damaging the conveyor 2, or the layboard 8 which supports the upper run of the conveyor 2, when no sheet is passing the flame, there is provided an air jet 9 consisting of a tube with a plurality of small apertures extending radially therethrough. The air jet 9 is connected with a source of compressed air, not shown, through a tube 10, FIGURE 2, and, a

, heat conductive coil 11 by which the compressed air is warmed before entering the air jet 9. During the passage of a sheet past the flame 6 the air curtain 12, FIGURE 1, emitted by the air jet 9 is directed against the under surface of the sheet. When, however, no sheet is passing the flame 6, the air curtain 12 causes the flame 6 to be directed upwards and towards the coil ll, which preferably consists of a copper tube partly shrouded by a shroud 13 to conserve the heat.

The application of the flame to a sheet causes moisture of condensation to accumulate on the surface to which the flame is applied and this must be removed before the sheet is delivered to the liquid-coating apparatus. For the purpose of removing the accumulated moisture of condensation, the conveyors 2 and 3 move the sheets beneath a dryer device which consists of an air blower 14, FIGURE 1, connected by a conduit 15 with a nozzle 16, the mouth 17 of which extends transversely across the conveyor 3 and is directed towards the upper run of the conveyor. Low pressure air is blown through the nozzle 16 on to the surface of a sheet as it is moved beneath the nozzle and removes the accumulated moisture of condensation on the upper surface of the sheet which is thereafter immediately introduced into the liquid-applying apparatus by the conveyor 3.

It is found that when a sheet is coated immediately after treatment as herein described by apparatus accord- In the embodiment of the invention described above,

the articles to be coated have been described as tinplate sheets, but it will be understood that the articles may be other than sheets, for example they may be tinplate can bodies open at the opposite ends thereof and which are to be fed to a lacquering device adapted to lacquercoat the interior or the exterior of the bodies. Machines are known for applying lacquer to the interior or the exterior of open-ended can bodies and it will be understood that such machines may be suitably modified to embody therein flame-treating and drying devices of the general character herein described although it will be understood that such devices must be modified to suit the conditions of the different types of machines to which they are appiied.

It will also be understood that, if desired, the sheets may be conveyed at one level by conveyors 1 and 2, in which case the conveyor 2 may be of wire mesh, or perforated, to permit the desired operation of the air jet 9.

I claim:

1. In an apparatus for liquid coating sheets, sheet conveying means, means for flame heating the whole surface of each sheet to which liquid coating is to be applied while the sheet is moving along on the conveying means, and means for directing air over the flame heated sheet surfaces to remove accumulated moisture of condensation, said conveying means including a second endless conveyor and a first endless conveyor disposed with its delivery end overlying the receiving end of said second conveyor, a transverse roller paralleling and spaced from the delivery end of the first conveyor in the direction of travel of the conveyed sheets and in position for supporting the trailing ends of sheets passing over the delivery end of said first conveyor, said flame heating means being disposed over the space between said roller and the delivery end of said first conveyor.

2. Apparatus as defined in claim 1 wherein there is included means for diverting the heating flame upwardly away from the conveyors when sheets are not passing the flame on said conveying means.

3. Apparatus as defined in claim 1 wherein there is included means for diverting the heating flame upwardly away from the conveyors when sheets are not passing the flame on said conveying means, said diverting means comprising means to provide an upward air blast directed at an angle against the flame in the space between the roller and the delivery end of the first conveyor.

4. Apparatus as defined in claim 3 together with a heating coil for preheating the air of said air blast overlying said second conveyor adjacent said flame heating means and in the path of the diverted heating flame.

5. An apparatus for flame treating members comprising conveying means for conveying members along a predetermined path and in spaced relation to one another, a burner directing a flame towards said conveying means and from one side of the path of the members carried by said conveying means for flame treating the members, said conveying means extending directly in the path of the flame from said burner and receiving the direct effect of said burner thereon and a major portion of the heat radiating therefrom in the absence of a member on said coriveying means, and means disposed on the other side of the path of the members from the burner for providing an air blast directed across the path of the members and at an angle towards the flame for diverting the flame from said conveying means when members are not passing the flame on said conveying means and diverting the air blast preheating the air of said air blast, whereby said air blast applies heat to the surface of the member being flame treated remote from the treated surface.

7. The apparatus of claim 5 together with a heating coil for preheating the air of said air blast, said heating coil being disposed adjacent to said burner and in the path of the flame when redirected by said air blast.

8. The apparatus of claim 7 wherein said burner normally directs the flame downwardly and in the direction of movement of said conveying means, and said air blast means is directed upwardly and in the direction of movement of said conveying means.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain June 24, 1949, 

